Numerous silane adhesive compositions have previously been developed for the purpose of bonding elastomeric materials, particularly silicone elastomer-based materials, to various inorganic substrates. Many of these silane adhesive compositions rely on various organo-functional silanes as the active bonding agent. Due to the highly organic nature of the organo-functional silane compounds, traditional silane adhesive compositions have relied on organic solvents in order to form a stable and workable solution. While some traditional silane adhesive compositions contain water in addition to an organic solvent, the organic solvent is usually always required in order to form a stable composition.
One example of an organic solvent-based silane adhesive composition is described in U.S. Pat. No. 3,022,196 as being a mixture of an unsaturated silane and an aminoalkyl silane. For utilization as a coating composition or an adhesive, the mixture is prepared as a solution in the presence of a water-miscible organic solvent. The adhesive composition may also contain a small amount of water in addition to the water-miscible organic solvent; however, the water-miscible organic solvent in such case predominates.
Another example of an organic solvent-based silane adhesive composition is described in U.S. Pat. No. 4,618,389 as being a mixture of an alkenyltrihydrocarbonoxy silane, a water-miscible solvent, and water.
U.S. Pat. No. 4,690,966 describes an adhesive composition based on a combination of an organo-functional silane and an aluminum zirconium metallo-organic complex dissolved or dispersed in an organic solvent. A polymer resin which may be a phenolformaldehyde resin, such as a phenolic resole, may be included. Here again, while the adhesive composition may contain a small amount of water, the organic solvent predominates.
In light of the continuing effort to eliminate volatile organic solvents from all chemical formulations for environmental purposes, a need presently exists for an aqueous silane adhesive composition which is largely free of any volatile organic solvent and which is dilutable with water.
In my co-pending application Ser. No. 08/284,829 filed Aug. 2, 1994 are disclosed and claimed water-dilutable compositions based on a combination of an amine-functional silane and a normally water-immiscible alkenyl-functional silane hydrolyzed in the presence of the amine-functional silane.